US5204167A - Diamond-coated sintered body excellent in adhesion and process for preparing the same - Google Patents
Diamond-coated sintered body excellent in adhesion and process for preparing the same Download PDFInfo
- Publication number
- US5204167A US5204167A US07/798,972 US79897291A US5204167A US 5204167 A US5204167 A US 5204167A US 79897291 A US79897291 A US 79897291A US 5204167 A US5204167 A US 5204167A
- Authority
- US
- United States
- Prior art keywords
- diamond
- substrate
- tungsten carbide
- sintered body
- film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 229910003460 diamond Inorganic materials 0.000 title claims abstract description 153
- 239000010432 diamond Substances 0.000 title claims abstract description 153
- 238000004519 manufacturing process Methods 0.000 title abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- 239000000758 substrate Substances 0.000 claims description 150
- 239000002344 surface layer Substances 0.000 claims description 72
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims description 71
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 238000002441 X-ray diffraction Methods 0.000 claims description 9
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 abstract description 23
- 239000000203 mixture Substances 0.000 abstract description 16
- 239000010408 film Substances 0.000 description 93
- 239000000047 product Substances 0.000 description 66
- 238000005520 cutting process Methods 0.000 description 34
- 238000005299 abrasion Methods 0.000 description 31
- 238000000151 deposition Methods 0.000 description 26
- 239000010410 layer Substances 0.000 description 26
- 230000008021 deposition Effects 0.000 description 21
- 238000012360 testing method Methods 0.000 description 19
- 239000011248 coating agent Substances 0.000 description 16
- 238000000576 coating method Methods 0.000 description 16
- 239000007789 gas Substances 0.000 description 15
- 238000000034 method Methods 0.000 description 15
- 239000000843 powder Substances 0.000 description 15
- 238000005261 decarburization Methods 0.000 description 14
- 229910021385 hard carbon Inorganic materials 0.000 description 14
- 239000000463 material Substances 0.000 description 14
- 229910052721 tungsten Inorganic materials 0.000 description 13
- 239000000919 ceramic Substances 0.000 description 11
- 229910002804 graphite Inorganic materials 0.000 description 11
- 239000010439 graphite Substances 0.000 description 11
- 238000003801 milling Methods 0.000 description 9
- 238000005530 etching Methods 0.000 description 8
- 239000010409 thin film Substances 0.000 description 8
- 239000010937 tungsten Substances 0.000 description 8
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 5
- 238000005229 chemical vapour deposition Methods 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- 229910001882 dioxygen Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000000227 grinding Methods 0.000 description 5
- 229910052750 molybdenum Inorganic materials 0.000 description 5
- 230000000737 periodic effect Effects 0.000 description 5
- 238000005240 physical vapour deposition Methods 0.000 description 5
- 239000007858 starting material Substances 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 229910015417 Mo2 C Inorganic materials 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 239000008246 gaseous mixture Substances 0.000 description 4
- 230000005283 ground state Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000009832 plasma treatment Methods 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 229910052581 Si3N4 Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- -1 tungsten carbides Chemical class 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000001069 Raman spectroscopy Methods 0.000 description 2
- 229910000676 Si alloy Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- QIJNJJZPYXGIQM-UHFFFAOYSA-N 1lambda4,2lambda4-dimolybdacyclopropa-1,2,3-triene Chemical compound [Mo]=C=[Mo] QIJNJJZPYXGIQM-UHFFFAOYSA-N 0.000 description 1
- 229910018404 Al2 O3 Inorganic materials 0.000 description 1
- 101100008044 Caenorhabditis elegans cut-1 gene Proteins 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 229910039444 MoC Inorganic materials 0.000 description 1
- 229910007277 Si3 N4 Inorganic materials 0.000 description 1
- 102100025490 Slit homolog 1 protein Human genes 0.000 description 1
- 101710123186 Slit homolog 1 protein Proteins 0.000 description 1
- ATCDNCMWCPJXNQ-UHFFFAOYSA-N [Nb].[Ta].[Ti].[W] Chemical compound [Nb].[Ta].[Ti].[W] ATCDNCMWCPJXNQ-UHFFFAOYSA-N 0.000 description 1
- ZTJWUVMPZRLXAB-UHFFFAOYSA-N [Ta].[Ti].[W] Chemical compound [Ta].[Ti].[W] ZTJWUVMPZRLXAB-UHFFFAOYSA-N 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- FQNHWXHRAUXLFU-UHFFFAOYSA-N carbon monoxide;tungsten Chemical group [W].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-] FQNHWXHRAUXLFU-UHFFFAOYSA-N 0.000 description 1
- 239000011195 cermet Substances 0.000 description 1
- 208000037998 chronic venous disease Diseases 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000003028 elevating effect Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 229910021397 glassy carbon Inorganic materials 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 description 1
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 229910003465 moissanite Inorganic materials 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910003468 tantalcarbide Inorganic materials 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
- C23C16/27—Diamond only
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/5001—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with carbon or carbonisable materials
- C04B41/5002—Diamond
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/02—Pretreatment of the material to be coated
- C23C16/0209—Pretreatment of the material to be coated by heating
- C23C16/0218—Pretreatment of the material to be coated by heating in a reactive atmosphere
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
- C23C30/005—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process on hard metal substrates
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31678—Of metal
Definitions
- This invention relates to a diamond-coated sintered body excellent in adhesion strength comprising a film of diamond or diamond-like carbon deposited on the surface of a substrate of a ceramics sintered body composed mainly of tungsten carbide and a process for preparing the same. More specifically, it relates to a diamond-coated sintered body excellent in adhesion strength which is suitable as the material for parts to be used in electrical industries, electronic industries, precise instrument industries, office instrument industries, etc. primarily for, for example, material for cutting tool, material for abrasion resisting tool or materials for decoration, and a process for preparing the same.
- Japanese Provisional Patent Publication No. 126972/1983 discloses a cemented carbide tool comprising at least one selected from carbides, nitrides, borides and oxides of the groups 4a, 5a and 6a elements and their compounds, mixtures thereof, or Al 2 O 3 , AlN, B 4 C, SiC, Si 3 N 4 , SiO 2 , as inner layer adjacent to the surface of a cemented carbide, and comprising diamond as outer layer.
- cemented carbide as the substrate comprises at least one carbide and nitride.
- the invention disclosed in the same Publication involves the problem of cumbersomeness of the process that the diamond film is required to be formed in an entirely separate reaction vessel after coating of the intermediate layer by the CVD method or the PVD method in order to form a diamond film with good quality. Also, as concerned with such cumbersomeness of the process, it has a problem that impurities are readily attached at the interface between the intermediate layer and the diamond film, whereby the adhesion strength of the diamond film, is lowered.
- Japanese Provisional Patent Publication No. 57802/1987 discloses a hard carbon coated part, comprising a compound thin film of W and C composed mainly of W 2 C with a thickness of 0.1 ⁇ m or more interposed between the hard carbon thin film and the substrate.
- the invention according to the same Publication has accomplished the improvement of adhesion strength as the result of formation of a diffusion layer generating WC at the interface between hard carbon and W 2 C when the intermediate layer as described above is coated on the surface of a substrate comprising a cemented carbide or ceramics, and subsequently hard carbon is coated on the surface of an intermediate layer, but it has the problem of cumbersomeness of the process that the hard carbon film is required to be formed in an entirely separate reaction vessel after formation of the intermediate layer by the CVD method or the PVD method, and there is also a problem that adhesion strength between the intermediate layer and the hard carbon thin film is inferior because impurities are readily attached on the intermediate surface.
- Japanese Provisional Patent Publication No. 166904/1987 discloses a hard carbon film coated cutting tool for working of ceramics materials, comprising a substrate of a ceramics sintered body composed mainly of silicon nitride, silicon carbide, zirconium oxide, aluminum oxide, and a thin film of hard carbon coated to 0.5 to 50 ⁇ m under low pressure on the surface thereof.
- the invention in the same Publication enables the cutting of a fine ceramics which is a difficultly cuttable material by use of a ceramics with high deformation resistance as the substrate and coating a thin film of hard carbon on the surface thereof, but, for example, there is a problem that adhesion strength between the substrate and the thin film deteriorates as the content of diamond in the hard carbon is increased, while abrasion resistance is lowered, if on the contrary, the content of diamond is decreased.
- Japanese Provisional Patent Publication No. 53269/1988 discloses a diamond-coated chip in cutting tool comprising a substrate of cemented carbide containing 1 to 4% by weight of Co and the balance of tungsten carbide in this substrate having a structure with a grain size of 2 to 10 ⁇ m.
- 57802/1987 comprises a diamond film deposited on the surface of the etching layer formed by etching Co existing on the surface of a cemented carbide by the acid treatment, and is free from the problem of cumbersomeness in the process and the deterioration of adhesion strength between the etching layer and the substrate.
- the problems that if the thickness of the etching layer becomes thick, the portion of Co removed by etching may sometimes remain as a void, whereby adhesion strength between the diamond film and the etching layer may be extremely lowered. To the contrary, if the thickness of the etching layer becomes thin, the generation of graphite during diamond deposition cannot be prevented enough.
- Japanese Provisional Patent Publication No. 99102/1988 discloses a diamond coated tungsten tool, comprising tungsten as the substrate and diamond film coated to 1 to 100 ⁇ m on said substrate.
- This invention in the same Publication has solved the problem of adhesion strength by use of tungsten as the substrate, in view of the diamond-coated tool of the prior art comprising a diamond thin film coated on the substrate surface of a cemented carbide or ceramics having the problem in adhesion strength between the thin film and the substrate.
- tungsten itself is soft and hence susceptible to plastic deformation, whereby there is the problem that its life is short when used as the cutting tool.
- Japanese Patent Publication No. 4586/1989 discloses a method in which the working strain is generated on the surface of cemented carbide by grinding with a grinding wheel for deposition of diamond, the respective work strain before and after grinding are determined as a half value widths of the X-ray diffraction line at the WC (100) crystal face, and subsequently, diamond film is coated on the surface of the substrate with its certain ratio.
- the invention in the same Publication resides in remarkable increase of the crystal nucleus of diamond by depositing a diamond on the substrate surface having a certain amount of work strain, whereby the film with fine structure is formed and also the adhesion strength between the film and the substrate is excellent.
- VIII group metal in the periodic table is contained in the cemented carbide of the substrate, there are problems such that graphite is readily formed on the surface of the substrate at the initial stage during diamond deposition.
- the present invention has solved the problems as described above, and specifically aims at providing a diamond-coated sintered body which is excellent in adhesion strength between the substrate and the diamond and/or diamond-like carbon film, and also practically applicable as the materials for the cutting tool, and a process for preparing the same.
- the present inventors have investigated about the surface state morphology of the substrate before and after diamond deposition in the case of depositing diamond film on the surface of a sintered body mainly composed of tungsten carbide, for example, cemented carbide, and consequently obtained firstly a knowledge, even when diamond film is deposited on the surface which is etched Co metal existing in the surface part of the substrate by etching treatment, deposition of a minute amount of graphite can be seen at the interface between the film and the substrate, although deposition of graphite at the initial stage of diamond deposition is inhibited.
- the diamond-coated sintered body excellent in adhesion strength of the present invention wherein the surface layer to at most 10 ⁇ m toward the inner portion from a surface of said substrate comprises recrystallized tungsten carbide, when diamond film and/or diamond like carbon formed on the surfac eof said substrate, and the average grain size of the recrystallized tungsten carbide in the surface layer is finer as compared with that existing in the inner portion excluding the said surface layer.
- the present inventors have also investigated about the kind of substrate, the thickness of the film and adhesion strength between the film and the substrate under the deposition conditions of diamond.
- a substrate comprising a sintered body mainly composed of tungsten carbide compared with another kinds of substrate, for example, cemented carbide or a cermet containing VIII group metal in periodic table
- generation of graphite at the initial stage of diamond deposition can be inhibited, and also by performing decarburization treatment into said substrate before diamond deposition, and subsequently deposition of diamond adhesion strength becomes further stronger, and consequently it is able to make a product practically available as material for cutting tools.
- the diamond-coated sintered body excellent in adhesion comprises a film of diamond and/or diamond-like carbon formed on the surface of a substrate of a sintered body comprising a hard phase composed mainly of tungsten carbide and inevitable impurities.
- the present inventors have further obtained knowledges that in a diamond-coated sintered body having a diamond film on the surface of a substrate comprising the hard phase composed mainly of tungsten carbide, adhesion strength between the film and the substrate differs depending on the amount of the strain existing on the surface of the substrate before deposition of the diamond and the deposition conditions of the film, and also that the adhesion strength is correlated with the half-value width of the X-ray diffraction line at the WC (100) face obtained by measurement with the Cr-K ⁇ line from the surface of the film of the diamond sintered body.
- the diamond-coated sintered body excellent in adhesion strength of the present invention comprises a diamond film and/or diamond-like carbon film deposited on the surface of a substrate of a sintered body comprising a hard phase composed mainly of tungsten carbide and inevitable impurities, wherein said diamond-coated sintered body has a half value width of X-ray diffraction line at the WC (100) face with the Cr-K ⁇ line from the surface of said coated film is 0.2° to 0.4° in terms of 2 ⁇ .
- the substrate in the diamond-coated sintered body excellent in adhesion strength of the present invention may be a substrate such that, when diamond is deposited on the surface layer of the substrate which is decarburized the surface layer may mainly compose of tungsten carbide.
- tungsten carbide a substrate such that, when diamond is deposited on the surface layer of the substrate which is decarburized the surface layer may mainly compose of tungsten carbide.
- the hard phase mainly composed of tungsten carbide and inevitable impurities
- the hard phase consists only of tungsten carbide or the case when it contains at least 50% by volume of tungsten carbide and other at least one component of carbides or carbonitrides of the group 4a, 5a and 6a metals of the periodic table and solid solutions of these.
- the hard phase consists of 90% by volume or more of tungsten carbide
- the case consisting only of tungsten carbide comprising WC or WC-W 2 C or the case consisting of WC-Mo 2 C, WC-W 2 C-Mo 2 C or WC-(W,Mo)C comprising 90% by volume or more of these tungsten carbides and the balance of molybdenum carbide is preferable, because adhesion strength between the film and the substrate is excellent, and also the strength of the substrate is excellent.
- the substrate comprises a sintered body composed of a hard phase of WC and inevitable impurities
- decarburization treatment mentioned below is carried out, and subsequently, diamond and/or diamond like carbon is deposited on the surface of said substrate, the surface portion of the substrate is transformed to a surface layer of recrystallized tungsten carbide as mentioned below, and consequently, diamond coated sintered body excellent in adhesion strength is obtained.
- the substrate comprises a sintered body composed of a hard phase mainly composed of WC and W 2 C mixedly present and inevitable impurities, particularly in case of the hard phase composed of 75% by weight or less of W 2 C and the balance of WC, the surface layer of WC is transformed to that of recrystallized WC without effecting the decarburizing treatment into the substrate by depositing a diamond film. Therefore, it is preferred to use the above substrate since a diamond coated sintered body is excellent in adhesion strength between the substrate and the film when the diamond is deposited on the surface of the above surface layer.
- the substrate in the diamond-coated sintered body of the present invention contains inevitable impurities in addition to the hard phase as described above, and as such inevitable impurities, there are impurities primarily contained in the starting materials, and the impurities entrained during the mixing and milling process of the starting materials.
- inevitable impurities there may be included, for example, Co, Ni, Fe, W, Cr, Mo, etc. entrained from the mixing vessel or ball, etc., and even when these inevitable impurities may be contained in an amount of 0.5% by volume in the substrate, lowering in adhesion strength between the substrate and the film is small, and also, there is the effect of reinforcing the strength of the substrate. Therefore, such case is also practically applicable.
- These substrates are preferred to have a constitution in which an average grain size of the tungsten carbide existing in the surface layer to at most 10 ⁇ m from the surface toward the inner portion is finer as compared with the average grain size of the tungsten carbide existing internally of the substrate except for the surface layer, because adhesion strength between the substrate and the film is more excellent, and also the quality of the diamond film can be enhanced.
- the grain size of the tungsten carbide in the surface layer is 1.0 ⁇ m or less, preferably 0.5 ⁇ m or less, the adhesion strength between the substrate and the film tends to be further excellent.
- the substrate is a sintered body comprising 4% by weight or less of a binding phase composed mainly of Co and/or Ni and the balance comprising a hard phase composed mainly of tungsten carbide and inevitable impurities
- the strength of the substrate itself is high, and yet the Co and/or Ni existing on the substrate surface is little in amount, and such Co and/or Ni can be easily removed, whereby the surface layer can be generated easily.
- the binding phase composed mainly of Co and/or Ni as herein mentioned shows the case when it consists only of Co and/or Ni, or the case when Fe, W, Cr, V, Zr, Cu and Mo exist in a minute amount as a solid solution in Co and/or Ni
- the hard phase composed mainly of tungsten carbide refers to the case when it consists only of tungsten carbide, or when it consists of a mixture of tungsten carbide and a cubic compound which inhibits the grain growth of tungsten carbide primarily, such as titanium carbide, tantalum carbide, niobium carbide, tungsten-titanium carbide, tungsten-tantalum-titanium carbide, tungsten-tantalum-niobium-titanium carbide, etc.
- the surface layer in the diamond-coated sintered body excellent in adhesion strength of the present invention can be controlled in the depth of it to about 50 ⁇ m toward the inner portion from the surface of the substrate, but because the treatment time for preparation of the surface layer is prolonged and the surface layer is provided for enhancing adhesion strength of the film, it should be preferably made as thin as possible.
- the depth of the surface layer which may differ depending on the use and the purpose, may be controlled to a thickness of, for example, 0.1 to 10 ⁇ m, preferably 0.5 to 5 ⁇ m.
- the average grain size of the recrystallized tungsten carbide in the surface layer it is finer than the average grain size of the tungsten carbide contained in the sintered body excluding the surface layer.
- the average grain size contained in the sintered body is 10 ⁇ m in an extreme case, the average grain size of the recrystallized tungsten carbide in the surface layer may be less than 10 ⁇ m, but for adhesion strength between the surface layer and the diamond film, the grain size of the recrystallized tungsten carbide should be desirably made such as 0.3 ⁇ m or less.
- the whole surface consists of a layer of recrystallized WC, or in other cases, depending on the thickness and the treatment conditions of the surface layer, the surface layer portion adjacent to the film is a layer of recrystallized WC and the surface layer at the further inner side of the substrate is a layer of recrystallized W 2 C layer or a layer comprising a mixture of recrystallized W 2 C and recrystallized WC, but it is preferred that the whole surface should consist of a layer consisting of recrystallized WC.
- the recrystallized tungsten carbide as mentioned here refers to one which is once converted from tungsten carbide to tungsten, and again crystallized out as tungsten carbide.
- the film of diamond and/or diamond-like carbon in the diamond-coated sintered body excellent in adhesion strength of the present invention may be one exhibiting properties of diamond or properties approximate to diamond such as electrical resistance, light transmittance, hardness, etc., specifically exhibiting a peak at 1333 cm -1 which has been said to be the Raman line of diamond when subjected to Raman spectroscopic analysis.
- such film includes the case when it consists only of diamond, the case when it contains diamond and other amorphous carbon or glassy carbon, etc., or the case when it consists of diamond-like carbon which has been said to exhibit the properties approximate to diamond although containing no diamond.
- the film side adjacent to the surface layer comprises diamond-like carbon and the film side apart from the surface layer is consisted of diamond.
- the thickness of the film which may differ depending on the use and the shape, is preferably made thicker, for example, 5 to 15 ⁇ m, for uses when abrasion resistance rather than impact resistance is emphasized, or thinner, for example, 0.1 to 5 ⁇ m, preferably 0.5 to 2 ⁇ m, for uses when impact resistance is emphasized such as milling cutter, and uses having sharp cutting blade such as drill or slitter.
- the half-value width in the diamond-coated sintered body of the present invention is obtained by measuring the X-ray diffraction line at the WC (100) face with the Cr-K ⁇ line from the surface of the film by means of a diffractometer with chromium target, a monochrometer of graphite single crystal, and determining the width of the diffraction line at the portion of 1/2 height of the diffraction peak at the WC (100) face from the background of the diffraction line. If the half-value width determined thus comes out of 0.2° to 0.4° adhesion strength of the film to the substrate is lowered.
- this half-value means may be considered to be fluctuated depending on the amount of the residual strain in the surface layer of the substrate and the WC grain size in the surface layer of the substrate.
- the value of this half-value width is applied to only when the substrate comprises a sintered body composed of a hard phase and inevitable impurities.
- the substrate in the process for forming the diamond-coated sintered body of the present invention can be made a dense sintered body by mixing and milling the starting materials composed mainly of tungsten carbide and then subjecting to hot press sintering or hot isostatic pressing treatment (HIP treatment) after normal sintering.
- HIP treatment hot isostatic pressing treatment
- the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention comprises setting a substrate of a sintered body composed mainly of tungsten carbide in a reaction vessel, decarburizing the surface layer of said substrate by elevating the temperature within said reaction vessel in a decarburizable atmosphere, and then performing a diamond film treatment, thereby converting the surface layer of said substrate to a surface layer comprising recrystallized tungsten carbide, and also making the average grain size of the recrystallized tungsten carbide in said surface layer finer than that of the tungsten carbide in the inner portion of said substrate.
- a specific example of the decarburizable atmosphere within the reaction vessel is preferably a gaseous mixture of hydrogen gas and oxygen gas, or a gaseous mixture of hydrogen gas and some kinds of organic gases comprising oxygen gas.
- the decarburization treatment prefers to be performed by the plasma treatment at a temperature of the substrate of 500° to 1200° C.
- the plasma treatment at this time can be effected with microwave or high frequency, and diamond coating treatment prefers to be performed subsequently within the same reaction vessel under the plasma treatment state, because there is almost no attachment of impurities between the surface layer and the film.
- the diamond-coated sintered body excellent in adhesion strength of the present invention which has a surface layer comprising tungsten carbide of fine grains, has increased amount of grain boundaries of tungsten carbide adjacent to the diamond film, and the diamond grains are embedded in shape of wedge in the grain boundaries of tungsten carbide, whereby adhesion strength between the surface layer and the diamond film are enhanced.
- the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention can remove a metal such as Co existing in the surface layer of the substrate, by the plasma treatment in a decarburizable atmosphere, particularly a gaseous mixture containing oxygen gas, also has a surface layer comprising recrystallized tungsten carbide of fine grains by the decarburization treatment into the substrate, and subsequently, diamond film is deposited on the surface of this substrate. Further the same treatment as described above performed in the same reaction vessel continuously will make difficult to attach the impurities at the interface between the film and the surface layer, whereby deposition of diamond is enhanced to form a dense and fine film.
- Tungsten carbide powder with an average grain size of 1.0 ⁇ m as starting material was ball-milled with balls made of cemented carbide in wet system, and a WC sintered body with an average grain size of 0.8 ⁇ m (containing about 0.5% by weight of a binding phase composed mainly of Co and/or Ni as inevitable impurities) was obtained by hot pressing process.
- the surface state of the substrate was as-sintered state prepared by re-sintering treatment and ground state by a grinding wheel, and subsequently, performed the decarburization treatment as shown below (A) and the diamond coating treatment (B), so that the products of the present invention 1 and 2 as shown in Table 1 were obtained.
- Example 1 After the surface of the substrate was ground, it was performed the decarburization treatment of (A) (provided that the treatment time is 60 min) and the diamond depositing treatment of (B) (provided that the treatment time is 20 min) in Example 1 to give the products of the present invention 3, 4 and 5 shown in Table 2.
- the diamond-coated sintered body of the prior art comprising an intermediate layer consisted of WC or W 2 C interposed between the substrate of a cemented carbide and a diamond film according to the CVD method or the PVD method could not be practically applied, because the adhesion strength of film was inferior and the cutting performance was substantially equal to the case when a film was directly formed on the substrate, the diamond-coated sintered body excellent in adhesion strength of the present invention has the tool life of being improved by 4 to 20-fold in the life test including abrasion resistance and chipping resistance in the cutting test as compared with Compare product in which diamond film is formed directly on the substrate.
- the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention can perform the decarburizing treatment of the substrate and the diamond coating treatment continuously in the same reaction vessel, and therefore, the influence of the impurities is very little, whereby there is the effect that the adhesion strength between the surface layer and the film can be remarkably enhanced.
- WC, MO 2 C with an average grain size of 3.0 ⁇ m were mixed and ball-milled with balls made of a cemented carbide in wet system and dried, and subsequently sintered by hot press method in vacuum to give a substrate of a sintered body composed mainly of WC.
- the surface state of the substrate is made as-sintered state or the ground state as shown in Table 3, and then subjected to the decarburization treatment under the conditions (C) shown below, and subsequently, under the diamond coating conditions (D) shown below in the same reaction vessel to give the products of the present invention 6, 7 and 9.
- the diamond film was deposited on the surface of the substrate under the conditions (D) shown below without the decarburization treatment under the conditions (C) shown below to give the product of the present invention 8.
- the above treatment (D) was performed on the surface of a commercially available silicon nitride type ceramics to give Compare product 6. Also, a commercially available substrate of cemented carbide being set in another reaction vessel subjected to the CVD treatment in a WF 6 -CH 4 -H 2 mixture gases to have W 2 C film, which thickness of it is about 1.5 ⁇ m, and subsequently, diamond film is deposited by application of the above treatment (D) to give Control product 7. Further, the above treatment (D) was performed on the surface of a commercially available W plate as the substrate, to give Comparative produce 8.
- the diamond-coated sintered body of the present invention is excellent in adhesion strength between the film and the substrate as compared with the diamond-coated sintered body of the prior art comprising a diamond film formed on each of a silicon nitride type ceramics substrate, a substrate of a cemented carbide having a layer of W 2 C or W substrate, and when used the diamond coated sintered body of the present invention as the material for cutting tools, the adhesion strength between the film and the substrate is remarkably excellent, so that the tool life of this prolongs by about 20% to 8-fold as compared with that of the prior art as described above.
- the process for preparing the diamond-coated sintered body excellent in adhesion of the present invention can make a surface layer constructed of fine grain composing mainly of tungsten carbide on the surface of this substrate, whereby there is the effect that adhesion strength between the surface layer and the film can be made more excellent.
- the diamond-coated sintered body of the present invention is excellent in adhesion strength of the film to the substrate as compared with the diamond-coated sintered body which is out of the scope of the present invention, and consequently, it has the effect being excellent by about 2.7 to 6.8-fold in abrasion resistance as compared with other ones.
- the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention is not substantially influenced by the amount of the strain of the surface layer before diamond coating, further, it can give a substrate having a surface layer comprising tungsten carbide of fine grains after deposition of diamond film, and consequently the diamond coated sintered body of the present invention has the effect of enhancing further adhesion strength of the film to the substrate.
- the diamond coated sintered body of the present invention composing of tungsten carbide mixedly existing WC and W 2 C as the substrate shows excellent adhesion strength of the film when it is used as a material for cutting tools, and consequently, it is excellent in abrasion resistance as compared with the compare products, too.
Abstract
There are disclosed a diamond-coated sintered body, comprising a film of diamond and/or diamond-like carbon deposited on the surface of a sintered body of a hard phase composed mainly of a mixture of W2C and WC and inevitable impurities and a process for preparing the same.
Description
This application is a continuation, of application Ser. No. 07/458,521, filed Dec. 28, 1989 now abandoned.
This invention relates to a diamond-coated sintered body excellent in adhesion strength comprising a film of diamond or diamond-like carbon deposited on the surface of a substrate of a ceramics sintered body composed mainly of tungsten carbide and a process for preparing the same. More specifically, it relates to a diamond-coated sintered body excellent in adhesion strength which is suitable as the material for parts to be used in electrical industries, electronic industries, precise instrument industries, office instrument industries, etc. primarily for, for example, material for cutting tool, material for abrasion resisting tool or materials for decoration, and a process for preparing the same.
Investigations have been made in the prior art about practical application of a diamond coated sintered body having film of diamond and/or diamond-like carbon deposited on the surface of a substrate comprising a sintered body of a metal, an alloy or ceramics. Such diamond-coated sintered body, because diamond is inferior in chemical bonding with other substances, involves the problem as the greatest task how the film of diamond and/or diamond-like carbon can be coated on the surface of the substrate under the state enhanced in adhesion. Particularly, in the case of materials for cutting tool, milling tools, drills and end mills, since they are used under the severest conditions, adhesion strength between the film and the substrate will become further important problem.
There have been a large number of proposals about use of diamond-coated sintered bodies which are enhanced in adhesion strength between the film of diamond and the substrate and can be used as the material for cutting tools, and they have comprised the representative examples which have made investigations from the aspect of the material of the substrate, wherein Japanese Provisional Patent Publications No. 126972/1983, No. 57802/1987, No. 166904/1987 and No. 99102/1988, and as a representative example which has made investigation from the aspect of the work strain on the surface of the substrate, there is Japanese Patent Publication No. 4586/1989.
Japanese Provisional Patent Publication No. 126972/1983 discloses a cemented carbide tool comprising at least one selected from carbides, nitrides, borides and oxides of the groups 4a, 5a and 6a elements and their compounds, mixtures thereof, or Al2 O3, AlN, B4 C, SiC, Si3 N4, SiO2, as inner layer adjacent to the surface of a cemented carbide, and comprising diamond as outer layer. In this time, cemented carbide as the substrate comprises at least one carbide and nitride. The invention according to this Japanese Provisional Patent Publication No. 126972/1983 attempts to solve the problem that diamond is transformed to graphite when a diamond is coated directly on a cemented carbide containing Co or Ni, by interposing an intermediate layer containing no metal such as Fe, Co and Ni, for example, tungsten carbide between the cemented carbide and the diamond film. However, although there is no great problem with respect to the adhesion strength between the intermediate layer formed by the chemical vapor deposition method (CVD method) or the physical vapor deposition method (PVD method) and the substrate, but adhesion strength between the diamond film and the intermediate film is inferior to make practical application impossible. Also, the invention disclosed in the same Publication involves the problem of cumbersomeness of the process that the diamond film is required to be formed in an entirely separate reaction vessel after coating of the intermediate layer by the CVD method or the PVD method in order to form a diamond film with good quality. Also, as concerned with such cumbersomeness of the process, it has a problem that impurities are readily attached at the interface between the intermediate layer and the diamond film, whereby the adhesion strength of the diamond film, is lowered.
Japanese Provisional Patent Publication No. 57802/1987 discloses a hard carbon coated part, comprising a compound thin film of W and C composed mainly of W2 C with a thickness of 0.1 μm or more interposed between the hard carbon thin film and the substrate. The invention according to the same Publication has accomplished the improvement of adhesion strength as the result of formation of a diffusion layer generating WC at the interface between hard carbon and W2 C when the intermediate layer as described above is coated on the surface of a substrate comprising a cemented carbide or ceramics, and subsequently hard carbon is coated on the surface of an intermediate layer, but it has the problem of cumbersomeness of the process that the hard carbon film is required to be formed in an entirely separate reaction vessel after formation of the intermediate layer by the CVD method or the PVD method, and there is also a problem that adhesion strength between the intermediate layer and the hard carbon thin film is inferior because impurities are readily attached on the intermediate surface.
Japanese Provisional Patent Publication No. 166904/1987 discloses a hard carbon film coated cutting tool for working of ceramics materials, comprising a substrate of a ceramics sintered body composed mainly of silicon nitride, silicon carbide, zirconium oxide, aluminum oxide, and a thin film of hard carbon coated to 0.5 to 50 μm under low pressure on the surface thereof. The invention in the same Publication enables the cutting of a fine ceramics which is a difficultly cuttable material by use of a ceramics with high deformation resistance as the substrate and coating a thin film of hard carbon on the surface thereof, but, for example, there is a problem that adhesion strength between the substrate and the thin film deteriorates as the content of diamond in the hard carbon is increased, while abrasion resistance is lowered, if on the contrary, the content of diamond is decreased.
Japanese Provisional Patent Publication No. 53269/1988 discloses a diamond-coated chip in cutting tool comprising a substrate of cemented carbide containing 1 to 4% by weight of Co and the balance of tungsten carbide in this substrate having a structure with a grain size of 2 to 10 μm. The invention in Japanese Provisional Patent Publication No. 53269/1988, as different from those having the intermediate layer of WC or W2 C between the diamond film or hard carbon film and the substrate in Japanese Provisional Patent Publications No. 126972/1983 and No. 57802/1987 as described above, comprises a diamond film deposited on the surface of the etching layer formed by etching Co existing on the surface of a cemented carbide by the acid treatment, and is free from the problem of cumbersomeness in the process and the deterioration of adhesion strength between the etching layer and the substrate. However, there are involved the problems that if the thickness of the etching layer becomes thick, the portion of Co removed by etching may sometimes remain as a void, whereby adhesion strength between the diamond film and the etching layer may be extremely lowered. To the contrary, if the thickness of the etching layer becomes thin, the generation of graphite during diamond deposition cannot be prevented enough.
Japanese Provisional Patent Publication No. 99102/1988 discloses a diamond coated tungsten tool, comprising tungsten as the substrate and diamond film coated to 1 to 100 μm on said substrate. This invention in the same Publication has solved the problem of adhesion strength by use of tungsten as the substrate, in view of the diamond-coated tool of the prior art comprising a diamond thin film coated on the substrate surface of a cemented carbide or ceramics having the problem in adhesion strength between the thin film and the substrate. However, since tungsten itself is soft and hence susceptible to plastic deformation, whereby there is the problem that its life is short when used as the cutting tool.
Japanese Patent Publication No. 4586/1989 discloses a method in which the working strain is generated on the surface of cemented carbide by grinding with a grinding wheel for deposition of diamond, the respective work strain before and after grinding are determined as a half value widths of the X-ray diffraction line at the WC (100) crystal face, and subsequently, diamond film is coated on the surface of the substrate with its certain ratio. The invention in the same Publication resides in remarkable increase of the crystal nucleus of diamond by depositing a diamond on the substrate surface having a certain amount of work strain, whereby the film with fine structure is formed and also the adhesion strength between the film and the substrate is excellent. However, since VIII group metal in the periodic table is contained in the cemented carbide of the substrate, there are problems such that graphite is readily formed on the surface of the substrate at the initial stage during diamond deposition.
The present invention has solved the problems as described above, and specifically aims at providing a diamond-coated sintered body which is excellent in adhesion strength between the substrate and the diamond and/or diamond-like carbon film, and also practically applicable as the materials for the cutting tool, and a process for preparing the same.
The present inventors have investigated about the surface state morphology of the substrate before and after diamond deposition in the case of depositing diamond film on the surface of a sintered body mainly composed of tungsten carbide, for example, cemented carbide, and consequently obtained firstly a knowledge, even when diamond film is deposited on the surface which is etched Co metal existing in the surface part of the substrate by etching treatment, deposition of a minute amount of graphite can be seen at the interface between the film and the substrate, although deposition of graphite at the initial stage of diamond deposition is inhibited. Secondly, there has been also obtained a knowledge that when oxygen gas is permitted to flow into the system before deposition of diamond for inhibiting completely generation of graphite according to the first knowledge, decarburization and removal of metal such as Co, etc. occur in the surface layer of the substrate, and when deposition of diamond is subsequently performed, the surface layer of the substrate will become the surface layer comprising recrystallized tungsten carbide, and the diamond film formed on the surface of the surface layer is excellent in adhesion and adhesion strength.
More specifically, the diamond-coated sintered body excellent in adhesion strength of the present invention wherein the surface layer to at most 10 μm toward the inner portion from a surface of said substrate comprises recrystallized tungsten carbide, when diamond film and/or diamond like carbon formed on the surfac eof said substrate, and the average grain size of the recrystallized tungsten carbide in the surface layer is finer as compared with that existing in the inner portion excluding the said surface layer.
The present inventors have also investigated about the kind of substrate, the thickness of the film and adhesion strength between the film and the substrate under the deposition conditions of diamond. In case of depositing diamond film on the surface of a substrate comprising a sintered body mainly composed of tungsten carbide compared with another kinds of substrate, for example, cemented carbide or a cermet containing VIII group metal in periodic table, generation of graphite at the initial stage of diamond deposition can be inhibited, and also by performing decarburization treatment into said substrate before diamond deposition, and subsequently deposition of diamond adhesion strength becomes further stronger, and consequently it is able to make a product practically available as material for cutting tools.
More specifically, the diamond-coated sintered body excellent in adhesion comprises a film of diamond and/or diamond-like carbon formed on the surface of a substrate of a sintered body comprising a hard phase composed mainly of tungsten carbide and inevitable impurities.
The present inventors have further obtained knowledges that in a diamond-coated sintered body having a diamond film on the surface of a substrate comprising the hard phase composed mainly of tungsten carbide, adhesion strength between the film and the substrate differs depending on the amount of the strain existing on the surface of the substrate before deposition of the diamond and the deposition conditions of the film, and also that the adhesion strength is correlated with the half-value width of the X-ray diffraction line at the WC (100) face obtained by measurement with the Cr-Kα line from the surface of the film of the diamond sintered body.
More specifically, the diamond-coated sintered body excellent in adhesion strength of the present invention comprises a diamond film and/or diamond-like carbon film deposited on the surface of a substrate of a sintered body comprising a hard phase composed mainly of tungsten carbide and inevitable impurities, wherein said diamond-coated sintered body has a half value width of X-ray diffraction line at the WC (100) face with the Cr-Kα line from the surface of said coated film is 0.2° to 0.4° in terms of 2θ.
The substrate in the diamond-coated sintered body excellent in adhesion strength of the present invention may be a substrate such that, when diamond is deposited on the surface layer of the substrate which is decarburized the surface layer may mainly compose of tungsten carbide. Specifically sintered bodies comprising tungsten carbide and inevitable impurities, or sintered bodies comprising at least 50% by volume of tungsten carbide, with the balance comprising at least one of carbides, nitrides of metals of the groups 4a, 5a and 6a (such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W) of the periodic table, or solid solutions of these.
Among them, in the case of a substrate comprising a sintered body of a hard phase mainly composed of tungsten carbide and inevitable impurities, since no VIII group metal in the periodic table exists on the surface of the sintered body, transformation of diamond to graphite will occur very little during deposition of diamond and this substrate is preferable to give an excellent film of diamond.
In the substrate of a sintered body comprising a hard phase mainly composed of tungsten carbide and inevitable impurities, when the hard phase consists only of tungsten carbide or the case when it contains at least 50% by volume of tungsten carbide and other at least one component of carbides or carbonitrides of the group 4a, 5a and 6a metals of the periodic table and solid solutions of these. Among them, particularly the case when the hard phase consists of 90% by volume or more of tungsten carbide, for example, the case consisting only of tungsten carbide comprising WC or WC-W2 C, or the case consisting of WC-Mo2 C, WC-W2 C-Mo2 C or WC-(W,Mo)C comprising 90% by volume or more of these tungsten carbides and the balance of molybdenum carbide is preferable, because adhesion strength between the film and the substrate is excellent, and also the strength of the substrate is excellent.
Particularly, when the substrate comprises a sintered body composed of a hard phase of WC and inevitable impurities, if decarburization treatment mentioned below is carried out, and subsequently, diamond and/or diamond like carbon is deposited on the surface of said substrate, the surface portion of the substrate is transformed to a surface layer of recrystallized tungsten carbide as mentioned below, and consequently, diamond coated sintered body excellent in adhesion strength is obtained. Also, when the substrate comprises a sintered body composed of a hard phase mainly composed of WC and W2 C mixedly present and inevitable impurities, particularly in case of the hard phase composed of 75% by weight or less of W2 C and the balance of WC, the surface layer of WC is transformed to that of recrystallized WC without effecting the decarburizing treatment into the substrate by depositing a diamond film. Therefore, it is preferred to use the above substrate since a diamond coated sintered body is excellent in adhesion strength between the substrate and the film when the diamond is deposited on the surface of the above surface layer.
The substrate in the diamond-coated sintered body of the present invention contains inevitable impurities in addition to the hard phase as described above, and as such inevitable impurities, there are impurities primarily contained in the starting materials, and the impurities entrained during the mixing and milling process of the starting materials. As the latter inevitable impurities, there may be included, for example, Co, Ni, Fe, W, Cr, Mo, etc. entrained from the mixing vessel or ball, etc., and even when these inevitable impurities may be contained in an amount of 0.5% by volume in the substrate, lowering in adhesion strength between the substrate and the film is small, and also, there is the effect of reinforcing the strength of the substrate. Therefore, such case is also practically applicable. These substrates are preferred to have a constitution in which an average grain size of the tungsten carbide existing in the surface layer to at most 10 μm from the surface toward the inner portion is finer as compared with the average grain size of the tungsten carbide existing internally of the substrate except for the surface layer, because adhesion strength between the substrate and the film is more excellent, and also the quality of the diamond film can be enhanced.
The case when the grain size of the tungsten carbide in the surface layer is 1.0 μm or less, preferably 0.5 μm or less, the adhesion strength between the substrate and the film tends to be further excellent.
On the other hand, in the case when the substrate is a sintered body comprising 4% by weight or less of a binding phase composed mainly of Co and/or Ni and the balance comprising a hard phase composed mainly of tungsten carbide and inevitable impurities, the strength of the substrate itself is high, and yet the Co and/or Ni existing on the substrate surface is little in amount, and such Co and/or Ni can be easily removed, whereby the surface layer can be generated easily. The binding phase composed mainly of Co and/or Ni as herein mentioned shows the case when it consists only of Co and/or Ni, or the case when Fe, W, Cr, V, Zr, Cu and Mo exist in a minute amount as a solid solution in Co and/or Ni, while the hard phase composed mainly of tungsten carbide refers to the case when it consists only of tungsten carbide, or when it consists of a mixture of tungsten carbide and a cubic compound which inhibits the grain growth of tungsten carbide primarily, such as titanium carbide, tantalum carbide, niobium carbide, tungsten-titanium carbide, tungsten-tantalum-titanium carbide, tungsten-tantalum-niobium-titanium carbide, etc.
The surface layer in the diamond-coated sintered body excellent in adhesion strength of the present invention can be controlled in the depth of it to about 50 μm toward the inner portion from the surface of the substrate, but because the treatment time for preparation of the surface layer is prolonged and the surface layer is provided for enhancing adhesion strength of the film, it should be preferably made as thin as possible. The depth of the surface layer, which may differ depending on the use and the purpose, may be controlled to a thickness of, for example, 0.1 to 10 μm, preferably 0.5 to 5 μm. As for the average grain size of the recrystallized tungsten carbide in the surface layer, it is finer than the average grain size of the tungsten carbide contained in the sintered body excluding the surface layer. For example, if the average grain size contained in the sintered body is 10 μm in an extreme case, the average grain size of the recrystallized tungsten carbide in the surface layer may be less than 10 μ m, but for adhesion strength between the surface layer and the diamond film, the grain size of the recrystallized tungsten carbide should be desirably made such as 0.3 μm or less.
As to the composition of the recrystallized tungsten carbide constituting the surface layer, in some cases, the whole surface consists of a layer of recrystallized WC, or in other cases, depending on the thickness and the treatment conditions of the surface layer, the surface layer portion adjacent to the film is a layer of recrystallized WC and the surface layer at the further inner side of the substrate is a layer of recrystallized W2 C layer or a layer comprising a mixture of recrystallized W2 C and recrystallized WC, but it is preferred that the whole surface should consist of a layer consisting of recrystallized WC.
The recrystallized tungsten carbide as mentioned here refers to one which is once converted from tungsten carbide to tungsten, and again crystallized out as tungsten carbide.
The film of diamond and/or diamond-like carbon in the diamond-coated sintered body excellent in adhesion strength of the present invention may be one exhibiting properties of diamond or properties approximate to diamond such as electrical resistance, light transmittance, hardness, etc., specifically exhibiting a peak at 1333 cm-1 which has been said to be the Raman line of diamond when subjected to Raman spectroscopic analysis. To describe in more detail, such film includes the case when it consists only of diamond, the case when it contains diamond and other amorphous carbon or glassy carbon, etc., or the case when it consists of diamond-like carbon which has been said to exhibit the properties approximate to diamond although containing no diamond. Particularly, there is also the case when the film side adjacent to the surface layer comprises diamond-like carbon and the film side apart from the surface layer is consisted of diamond. The thickness of the film, which may differ depending on the use and the shape, is preferably made thicker, for example, 5 to 15 μm, for uses when abrasion resistance rather than impact resistance is emphasized, or thinner, for example, 0.1 to 5 μm, preferably 0.5 to 2 μm, for uses when impact resistance is emphasized such as milling cutter, and uses having sharp cutting blade such as drill or slitter.
The half-value width in the diamond-coated sintered body of the present invention is obtained by measuring the X-ray diffraction line at the WC (100) face with the Cr-Kα line from the surface of the film by means of a diffractometer with chromium target, a monochrometer of graphite single crystal, and determining the width of the diffraction line at the portion of 1/2 height of the diffraction peak at the WC (100) face from the background of the diffraction line. If the half-value width determined thus comes out of 0.2° to 0.4° adhesion strength of the film to the substrate is lowered. Although what this half-value means is not clear, it may be considered to be fluctuated depending on the amount of the residual strain in the surface layer of the substrate and the WC grain size in the surface layer of the substrate. The value of this half-value width is applied to only when the substrate comprises a sintered body composed of a hard phase and inevitable impurities.
The substrate in the process for forming the diamond-coated sintered body of the present invention can be made a dense sintered body by mixing and milling the starting materials composed mainly of tungsten carbide and then subjecting to hot press sintering or hot isostatic pressing treatment (HIP treatment) after normal sintering.
When a metal such as Co exists in the surface layer of the substrate, carbon existed in the tungsten carbide in the surface layer of the substrate, oxygen in the decarburization treatment gas and Co in the surface layer of the substrate become a cobalt carbonyl, which is evaporated Co from the surface layer of the substrate, and also the tungsten carbide (WC) in the surface layer of the substrate becomes tungsten, W2 C or may be tungsten carbonyl by the decarburization treatment, and subsequently they are crystallized again as tungsten carbide by the diamond coating treatment, thereby forming a surface layer.
The process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention comprises setting a substrate of a sintered body composed mainly of tungsten carbide in a reaction vessel, decarburizing the surface layer of said substrate by elevating the temperature within said reaction vessel in a decarburizable atmosphere, and then performing a diamond film treatment, thereby converting the surface layer of said substrate to a surface layer comprising recrystallized tungsten carbide, and also making the average grain size of the recrystallized tungsten carbide in said surface layer finer than that of the tungsten carbide in the inner portion of said substrate.
In the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention, a specific example of the decarburizable atmosphere within the reaction vessel is preferably a gaseous mixture of hydrogen gas and oxygen gas, or a gaseous mixture of hydrogen gas and some kinds of organic gases comprising oxygen gas. In the case of a gaseous mixture of hydrogen gas and oxygen gas, it is necessary to take sufficient care, because explosion may occur depending on the mixing ratio, and particularly the case when it is a decarburizable atmosphere consisting of 0.1 to 5% by volume of oxygen and the balance of hydrogen is preferred, because safety is high, a surface layer comprising recrystallized tungsten carbide with finer grain size can be formed after diamond is deposited on the surface of said substrate, and adhesion strength between the surface layer and the film is also excellent. Some kinds of organic gases as herein mentioned may include methane, ethane, propane, butane, methanol, ethanol, propanol, butanol, methyl ether, ethyl ether, etc. When the substrate is heated with such decarburizable atmosphere, the decarburization treatment prefers to be performed by the plasma treatment at a temperature of the substrate of 500° to 1200° C. The plasma treatment at this time can be effected with microwave or high frequency, and diamond coating treatment prefers to be performed subsequently within the same reaction vessel under the plasma treatment state, because there is almost no attachment of impurities between the surface layer and the film.
The reasons why can be increased the adhesion strength between diamond film and the substrate in the present invention is considered as stated below. Namely, this is because graphite generated at an initial stage of the diamond deposition is used for carburization of a surface decarburized layer of the substrate, thereby graphite formed at interface between the surface layer and the film is decreased, and as the result, adhesion strength between the substrate and the film is heightened. Particularly, in case where the substrate comprises a sintered body composed of a hard phase of tungsten carbides mixedly composed of W2 C and WC and inevitable impurities, W2 C at the surface portion of the substrate becomes WC by diamond deposition, which also has the function of promoting formation of nuclei of diamond.
Further, the diamond-coated sintered body excellent in adhesion strength of the present invention, which has a surface layer comprising tungsten carbide of fine grains, has increased amount of grain boundaries of tungsten carbide adjacent to the diamond film, and the diamond grains are embedded in shape of wedge in the grain boundaries of tungsten carbide, whereby adhesion strength between the surface layer and the diamond film are enhanced.
The process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention can remove a metal such as Co existing in the surface layer of the substrate, by the plasma treatment in a decarburizable atmosphere, particularly a gaseous mixture containing oxygen gas, also has a surface layer comprising recrystallized tungsten carbide of fine grains by the decarburization treatment into the substrate, and subsequently, diamond film is deposited on the surface of this substrate. Further the same treatment as described above performed in the same reaction vessel continuously will make difficult to attach the impurities at the interface between the film and the surface layer, whereby deposition of diamond is enhanced to form a dense and fine film.
Tungsten carbide powder with an average grain size of 1.0 μm as starting material was ball-milled with balls made of cemented carbide in wet system, and a WC sintered body with an average grain size of 0.8 μm (containing about 0.5% by weight of a binding phase composed mainly of Co and/or Ni as inevitable impurities) was obtained by hot pressing process. The surface state of the substrate was as-sintered state prepared by re-sintering treatment and ground state by a grinding wheel, and subsequently, performed the decarburization treatment as shown below (A) and the diamond coating treatment (B), so that the products of the present invention 1 and 2 as shown in Table 1 were obtained.
As comparison, the same substrate above-mentioned was performed directly with the treatment (B) without the treatment (A) to give compare products 1 and 2 as shown in Table 1.
______________________________________
(A) The decarburization treatment:
Gas composition 99% by volume H.sub.2 - 1% by
volume O.sub.2
Gas pressure 60 Torr
Substrate temperature
950° C.
Microwave output 0.8 kw
Treatment time 30 min.
(B) Diamond coating treatment:
Gas composition 98% by volume H.sub.2 - 2% by
volume CH.sub.4
Gas pressure 90 Torr
Substrate temperature
1050° C.
Microwave output 1.0 kw
Treatment time 120 min.
______________________________________
By use of the products of the present invention 1, 2 and compare products 1, 2, turning tests were carried out under the conditions shown below, and the results shown in Table 1 were obtained.
______________________________________
Turning test conditions:
______________________________________
Workpiece Al - 20% Si alloy
Chip shape SPGN 120308
Cutting speed 200 m/min.
Feed rate 0.1 mm/rev
Depth of cut 0.5 mm
Cutting time 10 min.
Evaluation average amount of wear in flank
face (V.sub.B mm)
______________________________________
TABLE 1
______________________________________
Dia-
Substrate mond Results of
surface Surface layer
film cutting tests
Sample
before Grain Thick-
thick-
V.sub.B
Damage
No. treatment
size ness ness (mm) situation
______________________________________
Present
Ground 0.3 μm
1.5 μm
5 μm
0.02 Normal
pro- surface abrasion
duct 1
Present
As- 0.3 μm
1.5 μm
5 μm
0.02 Normal
pro- sintered abrasion
duct 2
surface
Com- Ground 5 μm
0.38 Flake off
pare surface film
pro-
duct 1
Com- As- 5 μm
0.40 Flake off
pare sintered film
pro- surface
duct 2
______________________________________
By use of WC powder with an average grain size of 1.0 μm (written as "a-WC"), WC powder with an average grain size of 3.0 μm (written as "b-WC"), WC powder with an average grain size of 5.0 μm (written as "c-WC") and Co powder, VC powder with an average grain size of 1 to 2 μm, they were formulated to a WC-0.5 wt. % VC-2 wt. % Co composition, mixed by ball milling, dried, press molded and sintered similarly as in Example 1 to give the respective substrates shown in Table 2. After the surface of the substrate was ground, it was performed the decarburization treatment of (A) (provided that the treatment time is 60 min) and the diamond depositing treatment of (B) (provided that the treatment time is 20 min) in Example 1 to give the products of the present invention 3, 4 and 5 shown in Table 2.
As comparison, by use of the same substrate above-mentioned, only the treatment (B) in Example 1 was performed to give Compare products 3, 4 and 5.
By use of the products of the present invention 3, 4, 5 and the Control products 3, 4, 5, milling tests were carried out to obtain the results shown in Table 2.
______________________________________
Milling cutting test conditions:
______________________________________
Workpiece hard carbon
Chip shape SPGN 120308
Cutting speed 300 mm/min.
Feed rate 0.1 mm/tooth
Depth of cut 0.5 mm
Cutting time 90 min.
Evaluation Average amount of wear in flank
wear (V.sub.B mm)
______________________________________
TABLE 2
__________________________________________________________________________
Kind of Average grain Diamond
starting size of WC
Surface layer
coating
Milling cutting
material internally of
Grain
Thick-
thick-
test results
Sample No.
WC substrate
size
ness ness V.sub.B (mm)
Damage situation
__________________________________________________________________________
This
invention
3 a-WC 0.8
μm
0.3 μm
1 μm
2 μm
0.09 Normal abrasion
4 b-WC 2.5
μm
0.3 μm
1 μm
2 μm
0.11 Normal abrasion
5 c-WC 4 μm
0.3 μm
1 μm
2 μm
0.10 Normal abrasion
Compare
product
3 a-WC 0.8
μm
-- -- 2 μm
0.35 Coating flake-
off, chipping
4 b-WC 2.5
μm
-- -- 2 μm
0.39 Coating flake-
off, chipping
5 c-WC 4 μm
-- -- 2 μ m
0.37 Coating flake-
off, chipping
__________________________________________________________________________
As contrasted to the fact that the diamond-coated sintered body of the prior art comprising an intermediate layer consisted of WC or W2 C interposed between the substrate of a cemented carbide and a diamond film according to the CVD method or the PVD method could not be practically applied, because the adhesion strength of film was inferior and the cutting performance was substantially equal to the case when a film was directly formed on the substrate, the diamond-coated sintered body excellent in adhesion strength of the present invention has the tool life of being improved by 4 to 20-fold in the life test including abrasion resistance and chipping resistance in the cutting test as compared with Compare product in which diamond film is formed directly on the substrate.
Also, the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention can perform the decarburizing treatment of the substrate and the diamond coating treatment continuously in the same reaction vessel, and therefore, the influence of the impurities is very little, whereby there is the effect that the adhesion strength between the surface layer and the film can be remarkably enhanced.
WC, MO2 C with an average grain size of 3.0 μm were mixed and ball-milled with balls made of a cemented carbide in wet system and dried, and subsequently sintered by hot press method in vacuum to give a substrate of a sintered body composed mainly of WC. The surface state of the substrate is made as-sintered state or the ground state as shown in Table 3, and then subjected to the decarburization treatment under the conditions (C) shown below, and subsequently, under the diamond coating conditions (D) shown below in the same reaction vessel to give the products of the present invention 6, 7 and 9. Also, the diamond film was deposited on the surface of the substrate under the conditions (D) shown below without the decarburization treatment under the conditions (C) shown below to give the product of the present invention 8.
______________________________________
(C) The decarburization treatment conditions:
Gas composition 98% by volume H.sub.2 - 2% by
volume O.sub.2
Gas pressure 60 Torr
Substrate temperature
930° C.
Microwave output 0.7 kw
Treatment time 30 min.
(D) Diamond coating treatment conditions:
Gas composition 98% by volume H.sub.2 - 2% by
volume CH.sub.4
Gas pressure 80 Torr
Substrate temperature
1060° C.
Microwave output 1.0 kw
Treatment time 120 min.
______________________________________
As Compare product, the above treatment (D) was performed on the surface of a commercially available silicon nitride type ceramics to give Compare product 6. Also, a commercially available substrate of cemented carbide being set in another reaction vessel subjected to the CVD treatment in a WF6 -CH4 -H2 mixture gases to have W2 C film, which thickness of it is about 1.5 μm, and subsequently, diamond film is deposited by application of the above treatment (D) to give Control product 7. Further, the above treatment (D) was performed on the surface of a commercially available W plate as the substrate, to give Comparative produce 8.
The products of the present invention 6, 7, 8 and 9, and Compare products 6, 7 and 8 were examined for the thickness of diamond film to obtain the results shown in Table 3. Also, the samples of the present products 6, 7 and 9 subjected to the treatment (C) were also examined for surface layer by X-ray diffraction and SEM to obtain the results shown together in Table 3.
By use of these products of the present invention 6, 7, 8 and 9, and Compare products 6, 7 and 8, the turning test and milling test were carried out under the conditions (E) and (F) shown below, and the average amount of wear in flank wear and the damage situation were observed to obtain the results shown in Table 4.
______________________________________
(E) Turning test conditions:
Workpiece Al - 18% Si alloy
Chip shape SPGN 120308
Cutting speed 226 m/min.
Feed rate 0.1 mm/teeth
Depth of cut 0.5 mm
Cutting time 20 min.
Evaluation average relief face abraded amount
(V.sub.B mm)
(F) Milling test conditions:
Workpiece Hard carbon
Tip shape SNCN 43ZFN
Cutting speed 356 m/min.
Feed rate 0.06 mm/teeth
Depth of cut 0.5 mm
Cutting time 60 min.
______________________________________
TABLE 3
__________________________________________________________________________
Substrate Surface layer
Thickness
Sample Surface
Grain size
Thickness
of diamond-
No. Composition
state of WC (μm)
film (μm)
__________________________________________________________________________
Present
WC sintered
As-sintered
0.2 μm
4.5 4.8
product 6
body state
Present
WC sintered
Ground 0.2 μm
4.2 4.7
product 7
body state
Present
WC sintered
As-sintered
-- -- 4.8
product 8
body state
Present
WC-5 vol % Mo.sub.2 C
Ground 0.2 μm
4.3 4.7
product 9 state
Compare
Si.sub.3 N.sub.4
Ground -- -- 4.9
product 6
ceramics state
Compare
Cemented W.sub.2 C coated
-- -- 4.8
product 7
carbide
Compare
W substrate
Ground -- -- 4.8
product 8 state
__________________________________________________________________________
TABLE 4
______________________________________
(E) Cutting test results
(F) Cutting test results
Sample Damage Damage
No. V.sub.B (mm)
situation V.sub.B (mm)
situation
______________________________________
Present
0.08 Normal 0.12 Normal
product 6 abrasion abrasion
Present
0.12 Normal 0.15 Normal
product 7 abrasion abrasion
Present
0.18 Normal abra-
0.23 Normal abra-
product 8 sion (Tendency sion (Tendency
to be finely to be finely
flaked-off) flaked-off)
Present
0.13 Normal 0.17 Normal
product 9 abrasion abrasion
Compare
0.45 Flaked off and
0.98 Blade edge
product 6 chipping defected after
10 min.
Compare
0.22 Normal abra-
0.32 Flaked off
product 7 sion but finely
flaked off
Compare
0.28 Plastic deforma-
0.52 Flaked off after
product 8 tion at blade 35 minutes
edge
______________________________________
From the results as described above, the diamond-coated sintered body of the present invention is excellent in adhesion strength between the film and the substrate as compared with the diamond-coated sintered body of the prior art comprising a diamond film formed on each of a silicon nitride type ceramics substrate, a substrate of a cemented carbide having a layer of W2 C or W substrate, and when used the diamond coated sintered body of the present invention as the material for cutting tools, the adhesion strength between the film and the substrate is remarkably excellent, so that the tool life of this prolongs by about 20% to 8-fold as compared with that of the prior art as described above.
Also, the process for preparing the diamond-coated sintered body excellent in adhesion of the present invention can make a surface layer constructed of fine grain composing mainly of tungsten carbide on the surface of this substrate, whereby there is the effect that adhesion strength between the surface layer and the film can be made more excellent.
By use of WC powder, Mo2 C powder as the starting materials, they were mixed and milled with balls made of a cemented carbide in wet system, and hot press sintered in vacuum to obtain a sintered body composed mainly of WC with an average grain size of 3.0 μm. After the surface of the substrate was made as-sintered state or ground state as shown in Table 5, it was subjected to the decarburization treatment under the conditions as described above (C), followed subsequently by the diamond deposition treatment under the conditions as described above (D) to give the respective samples shown in Table 5. (only the product of the present invention 11 has 95 vol. % WC--5 vol.Mo2 C as the composition of substrate, and others have 100% WC composition)
Next, the states of the surface layer of the substrate, and the thickness of the diamond film of the respective samples were examined by an optical microscope and a scanning electron microscope to obtain the results shown in Table 5. Also, through the surface of the diamond film, X-ray diffraction was carried out with Cr-Kα line under the conditions (G) shown below to determine the half-value width of the X-ray diffraction line at the WC (100) face, and the results are shown in Table 6.
______________________________________
(G) X-ray diffraction conditions:
______________________________________
Target Cr
Tube voltage 45 kv
Tube current 30 mA
Scale range 400 cps
Time constant 1 sec.
Scanning speed 1/4°/min.
Chart speed 10 mm/min.
Scattering slit 1°
Light receiving slit (RS)
0.3°
R.S.M. 0.8° (monochrometer
side)
S.S 1°
Scanning range 55° to 60°
______________________________________
Further, by use of the respective samples shown in Table 5, cutting tests were carried out under the conditions (H) shown below, and the average amount of wear in flank wear (VB) and the damaged state at that time were examined to obtain the results shown in Table 6.
______________________________________ (H) Turning test conditions: ______________________________________ Workpiece Hard carbon Shape SPGN 120308 Cutting speed 50 m/min. Feed rate 0.1 mm/rev Depth of cut 1 mm Cutting time 60 min. ______________________________________
TABLE 5
__________________________________________________________________________
Substrate Surface layer
Thickness
Sample
Surface
Kind of Grain size
Thickness
of diamond-
No. state grinding wheel
of WC (μm)
(μm)
film (μm)
__________________________________________________________________________
Present
As-sintered
-- 0.21 4.2 4.8
product 10
state
Present
As-sintered
-- 0.18 4.2 4.7
product 11
state
Present
Ground #230 Resinoid
0.20 4.0 4.8
product 12
state bond
Present
Ground #230 Resinoid
-- -- 4.8
product 13
state bond
Present
Ground #1000 Resinoid
-- -- 4.9
product 14
state bond
Present
Ground #140 Resinoid
-- -- 4.7
product 15
state bond
Present
Electrolyti-
-- 0.23 4.3 4.8
product 16
cally ground
state
Compare
Lap -- -- -- 4.7
product 9
state
Compare
Ground #120 Metal
-- -- 4.7
product 10
state bond
__________________________________________________________________________
TABLE 6
______________________________________
Half-value width
Sample at WC (100) face
Cutting test results
No. (°) V.sub.B (mm)
Damage situation
______________________________________
Present 0.28 0.09 Normal abrasion
product 10
Present 0.30 0.08 Normal abrasion
product 11
Present 0.28 0.10 Normal abrasion
product 12
Present 0.33 0.13 Normal abrasion
product 13 (Tendency to be finely
flaked off)
Present 0.22 0.21 Slightly flaked off but
product 14 normal abrasion
Present 0.28 0.19 Slightly flaked off but
product 15 normal abrasion
Present 0.26 0.08 Normal abrasion
product 16
Compare 0.18 0.54 Flaked off after
product 9 5 minutes
Compare 0.44 0.36 Flaked off
product 10
______________________________________
As can be seen from the above results, the diamond-coated sintered body of the present invention is excellent in adhesion strength of the film to the substrate as compared with the diamond-coated sintered body which is out of the scope of the present invention, and consequently, it has the effect being excellent by about 2.7 to 6.8-fold in abrasion resistance as compared with other ones.
Also, the process for preparing the diamond-coated sintered body excellent in adhesion strength of the present invention is not substantially influenced by the amount of the strain of the surface layer before diamond coating, further, it can give a substrate having a surface layer comprising tungsten carbide of fine grains after deposition of diamond film, and consequently the diamond coated sintered body of the present invention has the effect of enhancing further adhesion strength of the film to the substrate.
By using WC powder having an average grain size of 4.0 μm and W powder having an average grain size of 0.5 μm, these powders were mixed and milled by balls of cemented carbide with a predetermined amount of these powders, and after drying, this mixed powder was vacuum sintered by hot press to obtain sintered bodies of the present products 17, 18, 20, 21 and 23 shown in Table 7. Also, by using WC powder having an average grain size of 4.0 μm and W2 C powder having an average grain size of 1.5 μm, these powders were treated in the same process as mentioned above to obtain sintered bodies of the present products 19 and 22 shown in Table 7. By using these sintered bodies, after subjecting to the diamond film treatment shown in the following conditions (I), cutting test was carried out under the same conditions employed in Example 1 (provided that the cutting time is 20 minutes). The results are also shown in Table 7.
______________________________________
(I) Diamond coating treatment conditions:
______________________________________
Gas composition 97% by volume H.sub.2 - 3% by
volume CH.sub.4
Gas pressure 50 Torr
Gas flow amount 200 ml/min
Substrate temperature
960° C.
Treatment time 120 min.
______________________________________
TABLE 7
__________________________________________________________________________
W.sub.2 C in Thickness
substrate Surface layer
of diamond
Cutting test results
(wt %) composition
coating (μm)
V.sub.B (mm)
Damage situation
__________________________________________________________________________
Present
5 WC 5.3 0.054
Normal abrasion
product 17
Present
10 WC 5.0 0.051
Normal abrasion
product 18
Present
10 WC 5.2 0.048
Normal abrasion
product 19
Present
25 WC 5.1 0.050
Normal abrasion
product 20
Present
50 WC 5.2 0.049
Normal abrasion
product 21
Present
50 WC 5.2 0.052
Normal abrasion
product 22
Present
75 WC 5.0 0.075
Normal abrasion
product 23
__________________________________________________________________________
As seen from the results in Table 7 and Example 1 and Compare products 1 and 2 shown in Table 1, the diamond coated sintered body of the present invention composing of tungsten carbide mixedly existing WC and W2 C as the substrate shows excellent adhesion strength of the film when it is used as a material for cutting tools, and consequently, it is excellent in abrasion resistance as compared with the compare products, too.
Claims (8)
1. A diamond-coated sintered body having excellent adhesion strength, comprising a film of diamond and/or diamond-like carbon deposited on a surface of a substrate, wherein:
said substrate comprises a sintered body of a hard-phase composed mainly of tungsten carbide, and
said surface of said substrate comprises recrystallized tungsten carbide in the surface layer to at most 10 microns toward the inner portion from the surface of said substrate in which the average grain size of the recrystallized tungsten carbide in the surface layer is finer than the average grain size of the tungsten carbide in the inner portion of the substrate excluding the surface layer.
2. A diamond-coated sintered body as claimed in claim 1, wherein said hard phase comprises 50% by volume or more of tungsten carbide.
3. A diamond-coated sintered body as claimed in claim 1, wherein said tungsten carbide comprises 75% by weight or less of W2 C and the balance of WC.
4. A diamond-coated sintered body having excellent adhesion strength, comprising a film of diamond and/or diamond-like carbon deposited on a surface of a substrate, wherein:
the substrate comprises a sintered body of a hard-phase consisting essentially of tungsten carbide and recrystallized tungsten carbide in the surface layer to at most 10 microns toward the inner portion from the surface of the substrate in which the average grain size of the recrystallized tungsten carbide in the surface layer is finer than the average grain size of the tungsten carbide in the inner portion of the substrate excluding the surface layer, and the diamond coated sintered body has a half value width of X-ray diffraction line at the WC (100) face with the CR-Kα line through the surface of the coated film being 0.2° to 0.4° in terms of 2Θ.
5. A diamond-coated sintered body as claimed in claim 4, wherein the hard phase comprises 50% by volume or more of tungsten carbide.
6. A diamond-coated sintered body as claimed in claim 4, wherein the tungsten carbide comprises 75% by volume or less of W2 C and the balance of WC.
7. A diamond-coated sintered body having excellent adhesion strength comprising a film of diamond and/or diamond-like carbon deposited on a surface of a substrate, wherein the substrate comprises:
a sintered body having 4% or less by weight of a binding phase consisting essentially of at least one metal selected from the group consisting of Co and Ni and the balance of a hard phase consisting essentially of tungsten carbide, and
recrystallized tungsten carbide in the surface layer to at most 10 microns toward the inner portion from the surface of the substrate in which the average grain size of recrystallized tungsten carbide in the surface layer is finer than the average grain size of the tungsten carbide in the inner portion of the substrate excluding the surface layer.
8. A diamond-coated sintered body as claimed in claim 7, wherein said hard phase comprises 50% by volume or more of tungsten carbide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/798,972 US5204167A (en) | 1989-02-23 | 1991-11-29 | Diamond-coated sintered body excellent in adhesion and process for preparing the same |
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-44891 | 1989-02-23 | ||
| JP1044891A JPH0663092B2 (en) | 1989-02-23 | 1989-02-23 | Diamond-coated sintered body excellent in peeling resistance and method for producing the same |
| JP1102168A JP2620971B2 (en) | 1989-04-21 | 1989-04-21 | Diamond coated sintered body with excellent adhesion and method for producing the same |
| JP1-110992 | 1989-04-28 | ||
| JP1110992A JPH075406B2 (en) | 1989-04-28 | 1989-04-28 | Diamond-coated sintered body with excellent adhesion and method for producing the same |
| JP1-102168 | 1989-08-31 | ||
| US45852189A | 1989-12-28 | 1989-12-28 | |
| US07/798,972 US5204167A (en) | 1989-02-23 | 1991-11-29 | Diamond-coated sintered body excellent in adhesion and process for preparing the same |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US45852189A Continuation | 1989-02-23 | 1989-12-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US5204167A true US5204167A (en) | 1993-04-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/798,972 Expired - Fee Related US5204167A (en) | 1989-02-23 | 1991-11-29 | Diamond-coated sintered body excellent in adhesion and process for preparing the same |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US5204167A (en) |
Cited By (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5389400A (en) * | 1993-04-07 | 1995-02-14 | Applied Sciences, Inc. | Method for making a diamond/carbon/carbon composite useful as an integral dielectric heat sink |
| US5585176A (en) * | 1993-11-30 | 1996-12-17 | Kennametal Inc. | Diamond coated tools and wear parts |
| US5635256A (en) * | 1994-08-11 | 1997-06-03 | St. Gobain/Norton Industrial Ceramics Corporation | Method of making a diamond-coated composite body |
| US5674620A (en) * | 1994-08-11 | 1997-10-07 | Saint-Gobain/Norton Industrial Ceramics Corporation | Diamond-coated composite cutting tool and method of making |
| US5716170A (en) * | 1996-05-15 | 1998-02-10 | Kennametal Inc. | Diamond coated cutting member and method of making the same |
| US5759623A (en) * | 1995-09-14 | 1998-06-02 | Universite De Montreal | Method for producing a high adhesion thin film of diamond on a Fe-based substrate |
| US5837081A (en) * | 1993-04-07 | 1998-11-17 | Applied Sciences, Inc. | Method for making a carbon-carbon composite |
| US5891522A (en) * | 1995-05-24 | 1999-04-06 | Saint-Gobain Industrial Ceramics, Inc. | Composite article with adherent CVD diamond coating and method of making |
| US6027808A (en) * | 1996-11-11 | 2000-02-22 | Shinko Kobelco Tool Co., Ltd. | Cemented carbide for a drill, and for a drill forming holes in printed circuit boards which is made of the cemented carbide |
| EP1175949A1 (en) * | 2000-07-24 | 2002-01-30 | Toshiba Tungaloy Co., Ltd. | Coated cemented carbide |
| US6387502B1 (en) * | 1998-09-04 | 2002-05-14 | Ngk Spark Plug Co., Ltd. | Diamond-coated hard metal member |
| US6723389B2 (en) | 2000-07-21 | 2004-04-20 | Toshiba Tungaloy Co., Ltd. | Process for producing coated cemented carbide excellent in peel strength |
| US20040122515A1 (en) * | 2002-11-21 | 2004-06-24 | Xi Chu | Prosthetic valves and methods of manufacturing |
| US6929851B1 (en) * | 1998-06-10 | 2005-08-16 | Tdy Industries, Inc. | Coated substrate |
| US20060147631A1 (en) * | 2005-01-04 | 2006-07-06 | Lev Leonid C | Method for making diamond coated substrates, articles made therefrom, and method of drilling |
| US20070172660A1 (en) * | 2004-04-19 | 2007-07-26 | Yoshinori Koga | Carbon film |
| US20080057327A1 (en) * | 2004-05-19 | 2008-03-06 | Tdy Industries, Inc. | Al2O3 Ceramic Tool with Diffusion Bonding Enhanced Layer |
| US20090314136A1 (en) * | 2008-06-23 | 2009-12-24 | The Stanley Works | Method of manufacturing a blade |
| US20120144753A1 (en) * | 2009-08-20 | 2012-06-14 | Sumitomo Electric Industries, Ltd. | Cemented carbide and cutting tool using same |
| US8769833B2 (en) | 2010-09-10 | 2014-07-08 | Stanley Black & Decker, Inc. | Utility knife blade |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5389400A (en) * | 1993-04-07 | 1995-02-14 | Applied Sciences, Inc. | Method for making a diamond/carbon/carbon composite useful as an integral dielectric heat sink |
| US5604037A (en) * | 1993-04-07 | 1997-02-18 | Applied Sciences, Inc. | Diamond/carbon/carbon composite useful as an integral dielectric heat sink |
| US5837081A (en) * | 1993-04-07 | 1998-11-17 | Applied Sciences, Inc. | Method for making a carbon-carbon composite |
| US5585176A (en) * | 1993-11-30 | 1996-12-17 | Kennametal Inc. | Diamond coated tools and wear parts |
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| US5759623A (en) * | 1995-09-14 | 1998-06-02 | Universite De Montreal | Method for producing a high adhesion thin film of diamond on a Fe-based substrate |
| US5716170A (en) * | 1996-05-15 | 1998-02-10 | Kennametal Inc. | Diamond coated cutting member and method of making the same |
| US6027808A (en) * | 1996-11-11 | 2000-02-22 | Shinko Kobelco Tool Co., Ltd. | Cemented carbide for a drill, and for a drill forming holes in printed circuit boards which is made of the cemented carbide |
| US6929851B1 (en) * | 1998-06-10 | 2005-08-16 | Tdy Industries, Inc. | Coated substrate |
| US6387502B1 (en) * | 1998-09-04 | 2002-05-14 | Ngk Spark Plug Co., Ltd. | Diamond-coated hard metal member |
| US6723389B2 (en) | 2000-07-21 | 2004-04-20 | Toshiba Tungaloy Co., Ltd. | Process for producing coated cemented carbide excellent in peel strength |
| EP1175949A1 (en) * | 2000-07-24 | 2002-01-30 | Toshiba Tungaloy Co., Ltd. | Coated cemented carbide |
| US20040122515A1 (en) * | 2002-11-21 | 2004-06-24 | Xi Chu | Prosthetic valves and methods of manufacturing |
| US8501276B2 (en) | 2004-04-19 | 2013-08-06 | National Institute Of Advanced Industrial Science And Technology | Carbon film |
| US20070172660A1 (en) * | 2004-04-19 | 2007-07-26 | Yoshinori Koga | Carbon film |
| US8007909B2 (en) * | 2004-04-19 | 2011-08-30 | National Institute Of Advanced Industrial Science & Technology | Carbon film |
| US20080057327A1 (en) * | 2004-05-19 | 2008-03-06 | Tdy Industries, Inc. | Al2O3 Ceramic Tool with Diffusion Bonding Enhanced Layer |
| US20090186154A1 (en) * | 2004-05-19 | 2009-07-23 | Tdy Industries, Inc. | Method of forming a diffusion bonding enhanced layer on al2o3 ceramic tools |
| US20100227160A1 (en) * | 2004-05-19 | 2010-09-09 | Tdy Industries, Inc. | Al203 CERAMIC TOOLS WITH DIFFUSION BONDING ENHANCED LAYER |
| US7914913B2 (en) | 2004-05-19 | 2011-03-29 | Tdy Industries, Inc. | Al2O3 ceramic tool with diffusion bonding enhanced layer |
| US7968147B2 (en) | 2004-05-19 | 2011-06-28 | Tdy Industries, Inc. | Method of forming a diffusion bonding enhanced layer on Al2O3 ceramic tools |
| US8147992B2 (en) | 2004-05-19 | 2012-04-03 | TDY Industries, LLC | AL2O3 ceramic tools with diffusion bonding enhanced layer |
| US20060147631A1 (en) * | 2005-01-04 | 2006-07-06 | Lev Leonid C | Method for making diamond coated substrates, articles made therefrom, and method of drilling |
| US20090314136A1 (en) * | 2008-06-23 | 2009-12-24 | The Stanley Works | Method of manufacturing a blade |
| US8505414B2 (en) | 2008-06-23 | 2013-08-13 | Stanley Black & Decker, Inc. | Method of manufacturing a blade |
| US20120144753A1 (en) * | 2009-08-20 | 2012-06-14 | Sumitomo Electric Industries, Ltd. | Cemented carbide and cutting tool using same |
| US8801816B2 (en) * | 2009-08-20 | 2014-08-12 | Sumitomo Electric Industries, Ltd. | Cemented carbide and cutting tool using same |
| US8769833B2 (en) | 2010-09-10 | 2014-07-08 | Stanley Black & Decker, Inc. | Utility knife blade |
| US9393984B2 (en) | 2010-09-10 | 2016-07-19 | Stanley Black & Decker, Inc. | Utility knife blade |
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